Colonoscopies are done with “conscious sedation”, last 30 minutes and have the same stringent cardio respiratory monitoring. For this study we will follow our standard continuous cardio-respiratory monitoring, blood pressure measurements every 5 minutes. We also administer Oxygen 2 liters by nasal cannula routinely. We have an adverse event form to document any cases of cardio-respiratory depression or any other adverse event in a procedure involving conscious sedation. The physicians involved in conscious sedation have been certified in a “Conscious sedation and airway management” course conducted by Yale New Haven hospital.